class Singleton:
    # 　类属性
    __instance = None

    def __new__(cls, *args, **kwargs):
        if not cls.__instance:
            cls.__instance = super().__new__(cls, *args, **kwargs)
        return cls.__instance


s1 = Singleton()
s2 = Singleton()

print(s1)
print(s2)
print(Singleton())
print(Singleton())
print(Singleton())
print(Singleton())
print(Singleton())